Combined active and passive leg prosthesis system and a method for performing a movement with such a system

ABSTRACT

A lower limb prosthesis system and a method of controlling the prosthesis system to replace a missing lower extremity of an individual and perform a gait cycle are disclosed. The prosthesis system has a controller, one or more sensors, a prosthetic foot, and a movable ankle joint member coupled to the prosthetic foot. The movable ankle joint member comprises a hydraulic damping system that provides the ankle joint member damping resistance. The controller varies the damping resistance by providing volumetric flow control to the hydraulic damping system based on sensor data. In one embodiment, the hydraulic damping system comprises a hydraulic piston cylinder assembly, hydraulic fluid, and a valve to regulate the fluid. In one embodiment, the controller alters the damping resistance by modulating the valve to vary the hydraulic fluid flow within the hydraulic piston cylinder assembly of the movable ankle joint member based on sensor data.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of U.S. patentapplication Ser. No. 11/887,374, entitled COMBINED ACTIVE AND PASSIVELEG PROSTHESIS SYSTEM AND A METHOD FOR PERFORMING A MOVEMENT WITH SUCH ASYSTEM, and filed Jul. 30, 2009, which is a national stage entry ofInternational Patent Application No. PCT/SE2006/000445, entitledCOMBINED ACTIVE AND PASSIVE LEG PROSTHESIS SYSTEM AND A METHOD FORPERFORMING A MOVEMENT WITH SUCH A SYSTEM, and filed Apr. 18, 2006, theentireties of which are incorporated by reference herein.

BACKGROUND

1. Field

The present invention relates generally to a method for a combinedactive and passive leg prosthesis system and a combined active andpassive leg prosthesis system for replacing a missing lower extremity ofan individual to perform a gait cycle (take a step) by the legprosthesis system. The leg prosthesis system has at least one movablejoint and a drive unit to drive the movable joint.

More specifically, the present invention concerns a leg prosthesissystem intended for a person who has a leg amputated above or below theknee joint. Thus the system may comprise an articulated ankle joint orboth an articulated knee joint and an articulated ankle joint.

2. Description of the Related Art

A leg prosthesis system of the type stated above can be adjusted andused by wearers of a prosthesis at different amputation levels.

A person uses his entire body to perform a movement. A gait cycle, thatis two steps, is divided into a support phase and a swing phase. Thesupport phase is when the foot of the leg is in contact with the ground,and during the swing phase the foot swings freely in the air. Inwalking, one leg swings forward with a flexion in hip, knee and anklejoint while at the same time the arm on the opposite side swingsforward. The arm on the same side swings backward and helps to increasethe forward force and promotes balance. When the foot of the leg touchesthe ground, heel touching ground, the weight of the body is supportedand the forward fall is braked. The leg supports the body and drives itforward until the next leg takes over in placing the heel on the ground.

If one or more joints and muscles are missing, in this case in lowerextremities, there will be imbalance and more energy will be consumed.The more joints that are missing and the higher the amputation level,the more energy is required to perform a gait cycle.

A gait cycle, in this case for a leg prosthesis system, can beidentified as the movement performed by leg prosthesis system fromplacing the heel on the ground to the next placing of the heel on theground with the same leg.

A leg prosthesis system according to the invention can be used tofacilitate different types of gait cycles for the prosthesis wearer, forinstance to walk at varying speeds, to climb or descend stairs or walkon inclined surfaces.

With the leg prostheses that are available on the market, it isdifficult or even impossible for a leg prosthesis wearer to performcertain types of gait cycles.

The leg prosthesis systems that are being sold today are completelypassive, that is no external energy is supplied to the prosthesis inaddition to the prosthesis wearer's kinetic energy. A passive prosthesiscan only lock, dampen and decelerate a movement. With a good passive legprosthesis system according to prior art technique, a prosthesis wearercan handle most everyday situations, such as sit down, stand, walk onflat ground and descend stairs and slopes.

However, the energy that can be supplied to a passive leg prosthesissystem by the prosthesis wearer is in most cases not sufficient toperform more energy-consuming gait cycles, such as stand up from asitting position, quick increase of speed or climb a staircase or asteep slope. Another problem is to ensure ground clearance to reduce therisk of stumbling.

The manufacture and development of active leg prosthesis systems hasonly started recently, that is prostheses comprising motors and powersources. By supply of power, the leg prosthesis system helps theprosthesis wearer to perform certain gait cycles such as climb astaircase.

The technique chosen to supply power in active leg prosthesis systems,according to prior art technique, has resulted in problems, such as highmovement of inertia in moving the movable joints of the leg prosthesissystem. All parts have to be driven when performing a gait cycle and theenergy consumption in the leg prosthesis system will be high.

There is thus a need to improve prior art and many of the leg prosthesesthat are currently available on the market.

SUMMARY

An object of the present invention is to provide a leg prosthesis systemwhich eliminates one of the problems described above in a simple andeffective manner.

Another object of the invention is to provide a method of performinggait cycles with improved performance by means of a leg prosthesis.

The above objects and other objects that will be evident from thefollowing description are achieved by a device and a method according tothe claims.

A leg prosthesis system according to the invention comprises at leastone movable joint which can be switched between being actively driven orbeing passively braked. Furthermore the leg prosthesis system comprisesa control system for controlling the active and the passive unit in themovable joint. A number of transducers and sensors arranged on the legprosthesis system supply input data to the control system, and a powersource supplies power to control system, motors and transducers.

A leg prosthesis system according to the invention comprising controlsystem, power source and transducers can be provided with an ankle jointcomprising an active and a passive unit and/or a knee joint comprisingan active and a passive unit.

The leg prosthesis system according to the invention can also beadjusted to a prosthesis wearer who lacks both lower extremities, thatis who is double-leg-amputated. Each leg prosthesis system may, but neednot, comprise one common or two separate or communicating controlsystems.

According to one aspect of the present invention, a combined active andpassive leg prosthesis system is provided to replace a missing lowerextremity of an individual to perform a gait cycle by means of the legprosthesis system. The leg prosthesis system comprises at least onemovable joint and an active drive unit to supply power and drive themovable joint. Moreover the active drive unit is disconnectable fromdriving relation with the movable joint. By the active drive unit beingdisconnectable, low moment of inertia can be achieved in the movablejoint. The forward force in the natural swinging motion created by thewearer's body is then sufficient to move the joint. When the joint isdisconnected from driving, it is possible to brake the movement of thejoint when required. Braking of the movable joint performed by a passivebrake unit may be varied in braking force and be varied from acompletely unbraked (freely swinging) to a fully braked (locked) joint.The interaction between active driving and passive braking of a jointgives a prosthesis wearer a good possibility of performing gait cycleswith improved performance. An active drive unit which can be run in twodirections makes it possible to perform a movement in both directions ofthe joint if, in addition, it is possible to disconnect the active driveso as to perform a free movement of the joint which can be controlled bythe passive brake unit. Active and passive movements are a natural partof the gait pattern, which means that a system having such possibilitiescan more easily imitate the energy-saving way of the human body toperform movements.

Preferably, the active drive unit of the leg prosthesis system isdisconnected from driving relation with the movable joint during part ofthe gait cycle. For instance, the active drive unit can be disconnectedduring both the swing and the support phase.

Preferably, a passive brake unit acts on the movement of the joint whenthe active drive unit is disconnected from the joint. By using thepassive brake unit when the active drive unit is disconnected, theenergy-saving way of the human body to perform movements can beimitated.

Preferably, the leg prosthesis system according to the invention alsocomprises a control system adapted to control the active drive unit ofthe movable joint. The control system makes it possible to controldirection, force and speed of the active drive unit. The control systemalso makes it possible to activate driving only at points of time whenthe leg prosthesis system needs supply of extra power.

Preferably, the control system according to the invention is alsoadapted to control the passive brake unit of the movable joint. Acontrol system can be used to adjust the brake force from a completelyunbraked (freely swinging) to a fully braked (locked) joint. If thecontrol system controls both the active drive unit and the passive brakeunit, a number of advantages can be achieved since the leg prosthesissystem according to the invention can use the properties of both theactive drive unit and the passive brake unit and also the possibility ofswitching between driving and braking the movable joint.

Preferably the leg prosthesis system comprises both a movable knee jointand a movable ankle joint. A prosthesis wearer who lacks a knee joint,that is who is amputated above the knee joint, needs a leg prosthesiswhich has both knee joint and ankle joint. A prosthesis wearer who lacksboth lower extremities, that is who is double-leg-amputated, needs a legprosthesis system with at least two movable joints.

Preferably, the knee joint and the ankle joint are each arranged with adisconnectable active drive unit and a passive brake unit as well as acommon control system to control the movements of knee joint and anklejoint in a synchronized manner. In double amputation, two separate orcommunicating control systems may, but need not, be used. A legprosthesis system which is made up in this manner can use active andpassive techniques for both knee joint and ankle joint. When besides acontrol system coordinates the movement of the knee joint and the anklejoint, considerable improvements can be achieved compared with acompletely passive prosthesis, but also compared with an activeprosthesis which comprises a knee joint or a knee joint and an anklejoint which are active but not coordinated with a common control system.

Preferably the leg prosthesis system according to the inventioncomprises transducers for input data to the control system. Input datacan be sent to the system from, for instance, a key set, transducers,sensors (speed, position, angle, pressure), nerve sensors etc.

Preferably, the knee joint and the ankle joint move by switching betweenthe associated active drive unit and passive brake unit during a gaitcycle.

A leg prosthesis system according to the invention with a movable kneejoint and ankle joint which controls the direction, force and speed ofthe current control system for the active drive unit and the brake forcefor the passive brake unit in each joint independently of the otherjoint thus ensures an optimized and coordinated movement of the legprosthesis system.

The control system may use information from the entire leg prosthesissystem, for instance information from the knee joint when the anklejoint is to be controlled and vice versa.

According to one aspect of the present invention, a method is providedfor performing a gait cycle with a combined active and passive legprosthesis system, which replaces a lacking lower extremity of anindividual. The leg prosthesis system comprises at least one movablejoint and an active drive unit which supplies power and drives themovable joint. Moreover, the active drive unit is disconnected fromdriving relation with the movable joint during part of the gait cycle.By disconnecting the drive unit, it is, for instance, possible to usethe natural swinging movement during the swing phase in walking. Thusthe drive unit need not be adjusted to accomplish movements equivalentto free swinging. The active drive unit can instead be optimized fordriving, and energy saving can be ensured since the drive unit is notactivated during the entire time of use of the prosthesis.

Preferably the method comprises braking the movement of the joint, witha passive brake unit of the leg prosthesis system according to theinvention, when the active drive unit is disconnected from the joint.When the active drive unit is disconnected and the passive brake unit isconnected, the prosthesis can move freely by the forward force in thejoint in question created by the wearer's body, or the movement of thejoint can be braked.

Preferably the method comprises controlling of the drive unit and/or thebrake unit of the movable joint by a control system of the legprosthesis system according to the invention. By using a control system,it is possible to disconnect driving and/or activate the passive brakeunit at the correct point of time or taking the outer circumstances intoconsideration. The braking in the leg prosthesis system is a propertywhich advantageously is coordinated with the driving of the system toachieve a good result.

Preferably the method comprises supplying input data to the controlsystem from transducers of the leg prosthesis system. Input data issent, for instance, from a key set, transducers, sensors (which recordspeed, position, angle, pressure), nerve sensors etc.

The method preferably comprises controlling in a synchronized manner themovements of a knee joint and an ankle joint of the leg prosthesissystem. The knee joint and the ankle joint each have a disconnectableactive drive unit and a passive brake unit as well as a common controlsystem. In a leg prosthesis with both knee joint and ankle joint,improved possibilities are achieved for the prosthesis wearer since acontrol system which is common to both joints can coordinate themovements of knee joint and ankle joint.

The knee joint and the ankle joint preferably move by switching betweenthe associated drive unit and brake unit during a gait cycle.

Preferably the method comprises controlling, separately or in acommunicating manner, the movements of at least two movable joints ofleg prosthesis systems adjusted to a double-leg-amputated prosthesiswearer.

The control system may use information from the entire leg prosthesissystem, for instance information from the knee joint when the anklejoint is to be controlled and vice versa.

The method preferably comprises driving and braking of knee joint andankle joint, respectively, during a gait cycle.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described in more detail with reference to theaccompanying drawings, in which

FIG. 1 is a perspective view of a leg prosthesis system according to theinvention,

FIG. 2 illustrates the support phase of a gait cycle on a flat surface,

FIG. 3 illustrates the swing phase of a gait cycle on a flat surface,

FIG. 4 illustrates the support phase of a gait cycle when climbing astaircase, dashed lines indicating a corresponding gait cycle with apassive/rigid foot,

FIG. 5 illustrates the swing phase of a gait cycle when climbing astaircase,

FIG. 6 illustrates the support phase and the swing phase of a gait cyclewhen descending a staircase,

FIG. 7 illustrates the support phase of a gait cycle when climbing aslope,

FIG. 8 illustrates the swing phase of a gait cycle when climbing aslope,

FIG. 9 illustrates the support phase of a gait cycle when descending aslope,

FIG. 10 is a side view in cross-section of a knee in an activestraightening position,

FIG. 11 is a side view in cross-section of a knee in a passive brakingposition,

FIG. 12 is a side view in cross-section of a foot in an active positionaccording to the invention.

DETAILED DESCRIPTION

FIG. 1 shows a leg prosthesis system 1 with both knee joint 2 and anklejoint 3 according to the invention and a method of performing a gaitcycle with a leg prosthesis system. A prosthesis wearer can attach theprosthesis to the amputated leg by means of the leg-enclosing socket 13.Furthermore the socket 13 is attached to the movable knee joint 2 in asuitable manner and the knee joint is connected to the ankle joint 3 byinterconnecting elements 12 or the like. A foot prosthesis 14 isattached to the ankle joint 3 and can turn about the ankle joint 3.Additional components that may be included in a leg prosthesis systemare shock absorbers, angularly adjustable couplings etc.

Most of the people with an amputated leg have lost their leg below theknee joint. The present leg prosthesis system and/or method can be usedby prosthesis wearers who need a prosthesis with both knee joint andankle joint, but the invention can also be used for a prosthesis withonly an ankle joint or only a knee joint. The leg prosthesis systemand/or the method can also be used by prosthesis wearers who lack bothlower extremities, that is who are double-leg-amputated and need a legprosthesis system with at least two movable joints. One common or twoseparate and/or communicating control means may be used.

FIG. 2 shows the support phase for a gait cycle on a flat surface. Whenplacing the heel on the surface, FIG. 2.1, the body weight of theprosthesis wearer is applied to the leg prosthesis system. The kneejoint then allows flexion and the foot is plantar flexed, FIG. 2.2, thatis the foot blade moves away from the lower leg. Body weight andmuscular strength help to straighten knee joint and ankle joint tocentered standing, FIG. 2.3. In FIG. 2.4, the foot blade is compressedand energy is returned in FIG. 2.5. When performing this movement, fromFIG. 2.1 to FIG. 2.5, the leg prosthesis system is completely passive,passive braking of both ankle joint and knee joint. The joints arerotated by means of body weight and muscular strength from the remaininglower extremity. For extra power in the gait, for instance when walkingfaster, the active drive unit in the foot can be used in the position inFIG. 2.6 to push away.

FIG. 3 shows the swing phase in a gait cycle. FIG. 3.1 corresponds toFIG. 2.6 and when initiating a swing phase, FIG. 3.3, the active part ofthe ankle joint performs a dorsal flexion, that is the foot blade movestowards the lower leg. This dorsal flexion occurs to give the prosthesiswearer ground clearance, a safe distance between the foot and the groundto prevent stumbling. A passive foot does not manage the dorsal flexionfrom FIG. 3.2 to FIG. 3.3 but this movement of the foot blade requiressome kind of drive. The knee joint performs the swinging movement byusing the forward force created by the wearer's body, and the passivebraking controls the movement. When performing this movement, from FIG.3.3 after the dorsal flexion to FIG. 3.5, the leg prosthesis system iscompletely passive, passive braking of both ankle joint and knee joint.To provide extra force to the step, for instance when walking faster,the active drive unit in the knee joint can be used in the position inFIG. 3.4 to straighten the knee joint and move the lower leg forwardmore quickly.

To climb a staircase or slope, as illustrated in FIG. 4, FIG. 5, FIG. 7and FIG. 8, it is important for the knee joint and the ankle joint tocooperate. More energy is required in climbing, which means thatcooperating active drive of both ankle joint and knee joint canadvantageously help to perform the movement.

When descending a staircase or slope, as illustrated in FIG. 6 and FIG.9, the passive braking in both knee joint and ankle joint cooperates.

FIG. 4 to FIG. 6 illustrate the climbing of a staircase. FIG. 4 showsthe support phase when climbing a staircase. In FIG. 4.1 the foot ispositioned on the step, and balance is achieved. The leg prosthesissystem and/or the use of the method according to the invention then pushthe prosthesis wearer upwards, FIG. 4.2, to centered standing, FIG. 4.3.The control system makes it possible for the knee joint and the anklejoint to cooperate. The active drive unit in the knee joint strives tostraighten the knee joint while at the same time the active drive unitin the ankle joint presses the front of the foot towards the ground,FIG. 4.2. In this manner, the ankle joint helps to straighten the kneejoint, thereby reducing the energy consumption.

FIG. 4 illustrates the consequences of a passive foot, dashed lines, incombination with an active knee joint. The passive foot gives a higherknee joint position and the gait will be higher than it need be, and itwill be more difficult and require more energy for the user to raisehimself up on the step. The contact point of the passive foot on thestep is moved forwards compared with a foot which can perform a dorsalflexion, which results in also the center of gravity of the body havingto be moved forwards. The solid lines indicate how climbing a staircasecan be performed using a leg prosthesis according to the invention.

FIG. 5 illustrates the swing phase when climbing a staircase. Also inthis case the active drive units in the knee joint and the ankle jointare used. To prevent the prosthesis wearer from hitting the step withhis foot and stumbling in the swing phase when climbing a staircase, itis important that the knee joint and ankle joint create a safe distanceto the staircase. This is done by the active drive of the knee jointbending the joint and the drive of the ankle joint performing a dorsalflexion of the foot, FIG. 5.1. The leg prosthesis system according tothe invention has then created a safe distance to the staircase and alsoa good starting position for positioning for the next gait. FIG. 5 showsthe consequences of a completely passive system, dashed lines. The kneejoint does not bend the foot away, and the foot instead bumps into thestaircase.

FIG. 6 illustrates the descending of a staircase. Here both knee jointand ankle joint are mainly passive. The movement, FIG. 6.1 to FIG. 6.3,brakes the fall of the body by means of the passive brake units in kneejoint and ankle joint. The dashed lines indicate the consequences of apassive foot which is not capable of performing a dorsal flexion. Theactive drive units can optionally be used to help straighten knee jointand ankle joint in the swing phase.

FIG. 7 to FIG. 9 illustrate walking on a very sloping surface. The legprosthesis system according to the invention then functions in the sameway as when climbing a staircase. The angle of knee joint and anklejoint is the only thing that distinguishes the climbing of a staircasefrom walking on a very sloping surface. When walking on a slightlysloping surface, the walking can be more resembled to walking on flatground.

FIG. 4, FIG. 5, FIG. 7 and FIG. 8 illustrate ordinary situations whichrequire much energy to be managed. By letting the leg prosthesis system1 cooperate with the prosthesis wearer's body and existing lowerextremities, it is possible to imitate the energy-saving way of thehuman body to perform the movement. For minimum consumption of energy,all joints in the lower extremities are allowed to cooperate, and theremaining stump of the prosthesis wearer can cooperate with the at leastone movable joint in the leg prosthesis system. The leg prosthesissystem should supplement the prosthesis wearer and should preferably,but not restrictively, be controlled by him or her.

With a leg prosthesis system 1 and/or a method according to theinvention, the disconnectable active drive unit 4, 4′ of a knee joint orankle joint makes it possible for the system and the method to use acombination of active and passive operation. The control system 15 canselect the optimal method of performing a movement. The knee joint 2 canbe active while the ankle joint 3 is passive and vice versa. Forexample, the knee joint 2 can perform the swinging movement in the swingphase using only the passive brake unit 2 while the ankle joint 3 usesits active drive unit for dorsal flexion of the foot in order to createextra ground clearance.

FIG. 10 and FIG. 11 are side views in cross-section of a knee jointwhich, for instance, may be included in the leg prosthesis system 1. Thesocket 13 is connected to the movable knee joint 2 which in turn isconnected to a hydraulic piston 9 via a link arm 10. FIG. 11 shows howthe piston 9 is moved when the knee joint is angled. FIG. 10 shows aknee joint 2 according to the invention in its active state with a driveunit 4, a brake unit 5 and a control system 15. In this embodiment, thebrake unit 5 involves throttling of the hydraulic oil which providesbraking/dampening of the movement of the joint. The battery 11 drivesthe hydraulic pump 6 of the drive unit 4 via a motor (not shown) foroperating the valve 8 of the brake unit 5. The battery 11 also drivesthe control system 15 and transducers and sensors (not shown) of the legprosthesis system 1. The control system 15 in turn controls the driveunit 4 and the brake unit 5 and receives input data from transducers andsensors; in addition the control system 15 coordinates the movements ofthe knee joint 2 and the ankle joint 3.

For activation of the drive unit 4, according to FIG. 10, the hydraulicpump 6 is started, the pressure increases on one side of the pump 6 and,via one of the ducts which open adjacent to the spring 17, the valvecone 7 is pressed aside and the duct system of the drive unit willcommunicate with the cylinder 16 where the piston 9 works and thus thepump 6 actuates the piston 9 in one or the other direction. When theactive drive unit 4 is activated, the valve 8 in the passive brake unit5 should be completely closed to be able to use the maximum efficiencyof the hydraulic pump 6. The active drive unit can drive the knee joint2 in both directions, in the direction towards a straightened knee jointand in the direction to bend the knee joint. In FIG. 10, the activedrive unit acts to straighten the knee joint 2. When the piston 9 ismoved in the cylinder 16, it acts on the link arm 10 which in turn actson the knee joint 2 to perform a movement. Alternative types of drivingand motors can be used for the leg prosthesis system other than thosementioned above.

According to FIG. 11 the drive unit 4 is disconnected by the hydraulicpump 6 being switched off. The pressure decreases and the spring 17presses the valve cone 7 back to its rest position, that is the valvecone 7 closes the ducts to the drive unit 4. The brake unit 5 isactivated when the drive unit 4 is disconnected. A movement of the kneejoint 2 actuates the piston 9 via the link arm 10, the hydraulic oil inthe cylinder 16 is pressed through the valve 8 of the brake unit 5 andthe degree of braking/dampening can be adjusted by varying the openingdegree of the valve 8. The braking can be varied in brake force and canbe varied from a completely unbraked (freely swinging) to a completelybraked (locked) knee joint 2.

The foot 14 with the ankle joint 3 according to FIG. 12 is shown in itsactive state and functions similarly to the knee joint according to FIG.10 and FIG. 11. To activate the drive unit, the hydraulic pump 6′ isstarted, the pressure is increased on one side of the pump 6′ and viaone of the ducts which open adjacent to the spring 17′, the valve cone7′ is pressed aside and the duct system of the drive unit willcommunicate with the cylinder 16′ where the piston 9′ works. In thismanner, the pump 6′ actuates the piston 9′ in one or the otherdirection. When the active drive unit 4′ is activated, the valve 8′ inthe passive brake unit 5′ should be completely closed to be able to usethe maximum efficiency of the hydraulic pump 6′. The piston 9′ actuatesthe link arm 10′ which in turn actuates the ankle joint 3 to perform amovement of the foot 14 relative to the interconnecting element 12. Thedrive unit 4′ is disconnected by the hydraulic pump 6′ being switchedoff. The pressure decreases and the spring 17′ presses the valve cone 7′back to its rest position, that is the valve cone 7′ closes the ducts tothe drive unit 4′. The brake unit 5′ in FIG. 12 is then activated; innormal working conditions the hydraulic pump 6′ is then switched off.

A movement of the ankle joint 3 in the passive state actuates the piston9′ via the link arm 10′, the hydraulic oil in the cylinder 16′ ispressed through the valve 8′ of the brake unit 5′ and the brake forcecan be adjusted by varying the opening degree of the valve 8′. Thebraking can be varied in brake force and can be varied from a completelyunbraked (freely swinging) to a fully braked (locked) ankle joint 3.

If the leg prosthesis system 1 merely comprises a foot prosthesis 3according to the invention, for instance at an amputation level belowthe knee joint, the foot prosthesis still needs a battery 11′ and acontrol unit 15′ which may then be arranged, for instance, around theinterconnecting element or on a leg-enclosing socket.

It goes without saying that the invention should not be consideredlimited to the embodiments described above and illustrated in thedrawings, with the described variants and alternatives, and can bemodified additionally in various ways within the scope of the appendedclaims.

What is claimed is:
 1. A lower limb prosthesis for replacing a missinglower extremity of an individual, said lower limb prosthesis comprising:a prosthetic foot member; a movable ankle joint member coupled to theprosthetic foot member, the ankle joint member comprising a hydraulicassembly comprising a hydraulic cylinder, a piston configured to moveaxially within the hydraulic cylinder between a first hydraulic chamberon one side of the piston and a second hydraulic chamber on an oppositeside of the piston as the prosthetic foot member moves relative to theankle joint member, the hydraulic chambers are defined in the hydrauliccylinder at least in part by the piston, and a valve actuatable tofluidly communicate the first and second hydraulic chambers, the valveconfigured to regulate hydraulic fluid flow between the hydraulicchambers so as to vary damping resistance of the ankle joint member; oneor more sensors configured to sense one or more parameters associatedwith the motion of the lower limb prosthesis during ambulation; and acontroller configured to receive input data from the one or more sensorscorresponding to the one or more sensed parameters, the controllerconfigured to control the operation of the valve to selectively actuatethe valve to vary the damping resistance of the ankle joint member basedat least in part on the one or more sensed parameters.
 2. The lower limbprosthesis of claim 1, wherein the controller is further configured tocontrol a motor to move the valve to an open position so that anorientation of the prosthetic foot member relative to the ankle jointmember varies during ambulation.
 3. The lower limb prosthesis of claim2, wherein opening the valve to a fully open position allows the anklejoint member to operate in an unbraked or freely swinging manner.
 4. Thelower limb prosthesis of claim 1, wherein the one or more sensedparameters are selected from the group consisting of acceleration,speed, angular velocity, position, ground inclination angle, andpressure.
 5. The lower limb prosthesis of claim 1, wherein the movementof the piston results in an adjustment of an angle between the anklejoint member and the prosthetic foot member, thereby altering anorientation of the ankle joint member relative to the prosthetic footmember.
 6. A lower limb prosthesis for replacing a missing lowerextremity of an individual, said lower limb prosthesis comprising: aprosthetic foot member; an ankle joint member pivotably coupled to theprosthetic foot member, the ankle joint member comprising a hydraulicdamping system; and a controller configured to receive input data fromone or more sensors on the lower limb prosthesis, to determine a dampingresistance adjustment needed for the lower limb prosthesis based atleast in part on the received input data, and to communicate an outputsignal to modify a damping resistance of the ankle joint member, whereinthe hydraulic damping system is configured, based at least in part onthe output signal from the controller, to regulate flow of a hydraulicfluid to adjust the damping resistance provided by the hydraulic dampingsystem to the pivotable ankle joint member, and wherein the hydraulicdamping system comprises a hydraulic cylinder and a piston configured tomove axially within the hydraulic cylinder between a first hydraulicchamber on one side of the piston and a second hydraulic chamber on anopposite side of the piston, the first and second hydraulic chambers aredefined in the hydraulic cylinder at least in part by the piston.
 7. Thelower limb prosthesis of claim 6, wherein the input data is related to aparameter selected from the group consisting of acceleration, speed,angular velocity, position, ground inclination angle, and pressure. 8.The lower limb prosthesis of claim 6, wherein the hydraulic dampingsystem comprises a valve actuatable to fluidly communicate the first andsecond hydraulic chambers, the valve is configured to regulate hydraulicfluid flow between the hydraulic chambers so as to vary the dampingresistance of the ankle joint member.
 9. The lower limb prosthesis ofclaim 8, wherein the movement of the piston results in an adjustment ofan angle between the ankle joint member and the prosthetic foot member,thereby altering an orientation of the ankle joint member relative tothe prosthetic foot member.
 10. The lower limb prosthesis of claim 8,wherein the controller is further configured to control a motor to movethe valve to an open position so that an orientation of the prostheticfoot member relative to the ankle joint member varies during ambulation.11. The lower limb prosthesis of claim 10, wherein opening the valve tothe open position allows the ankle joint member to operate in anunbraked or freely swinging manner.
 12. The lower limb prosthesis ofclaim 6, wherein the piston is configured to move axially within thehydraulic cylinder when the piston is not locked by the controller. 13.The lower limb prosthesis of claim 6, further comprising an active driveunit arranged to actively drive the ankle joint member during at least aportion of a gait cycle by providing power to the ankle joint member,wherein the power causes the ankle joint member to perform a movement.14. The lower limb prosthesis of claim 13, wherein the active drive unitcomprises a hydraulic pump.
 15. The lower limb prosthesis of claim 6,wherein the input data comprises position data.
 16. The lower limbprosthesis of claim 15, wherein the one or more sensors comprise aposition sensor.
 17. A method of controlling a lower leg prosthesis forreplacing a missing lower extremity of an individual, said methodcomprising: sensing parameters related to motion of the lower legprosthesis with one or more sensors and generating input data based onthe parameters; transmitting a signal based on the input data from theone or more sensors to a controller; determining, based at least in parton the input data, a damping resistance adjustment for the lower legprosthesis; and adjusting a damping resistance of a hydraulic anklemodule of the lower leg prosthesis via a motor actuatable valve, thehydraulic ankle module comprising an ankle joint and a piston axiallyslidable in a hydraulic cylinder.
 18. The method of claim 17, whereinthe valve is configured to communicate a first hydraulic chamber and asecond hydraulic chamber in the hydraulic cylinder, the valve isconfigured to regulate hydraulic fluid flow between the first and secondhydraulic chambers so as to vary the damping resistance of the hydraulicankle module.
 19. The method of claim 18, wherein adjusting the dampingresistance of the hydraulic ankle module includes opening the valve sothat the hydraulic ankle module pivots relative to a prosthetic footmember coupled to the hydraulic ankle module during ambulation.
 20. Themethod of claim 19, wherein axially sliding the piston in the hydrauliccylinder results in adjusting an angle between the hydraulic anklemodule and the prosthetic foot member coupled to the hydraulic anklemodule, thereby altering an orientation of the hydraulic ankle module.